Fix empty args for redis mget command

[denisov-vlad]

Summary

• avoid issuing Redis mget when there are no sticky bucket keys
• wrap Redis mget calls with error handling so failures are logged instead of crashing

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Codex Task

Issue: #100

[Copilot]

Pull request overview

This PR fixes a bug where the Redis mget command would be called with an empty array of keys, which could cause issues. It also improves error handling and logging for Redis sticky bucket operations.

• Adds a guard to prevent calling Redis mget with empty keys array
• Refactors promise chain to async/await with try-catch error handling
• Enhances error logging with additional context (error object and raw values)

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